Process for the manufacture of primary organic phosphines



atent iitice attests Patented Dec. ll, 1952 cngesellsciait y ranltiu arn h No Drawing. File Claims priority,

The present invention relates to a process for the manufacture of primary organic phosphines.

it is known to prepare alkyl-phosphines by different methods. it is possible, for example, to disproportionate nlkyl derivatives of hypophosphorous acid, which are acessible with great difiiculty only, according to the equation:

The theoretically obtainable yield of primary alkyl phosphine l t-PR amounts in this reaction to 33.3% and is in pra tice in most cases considerably smaller.

When phosphonium iodide is reacted with alliyl iodide and oxide alltyl-phosphines are likewise obtained in eld of about 38% only in the form of a mixture of all three phosphines.

Furthermore alkyi-phosphines can be produced according to the equation The extremely sensitive monosodium-phosphine used as starting material can only be app d in liquid ammonia or together with triphenyl-methyl sodium in the high dilution of mol per liter. in the reaction a yield of 50% can only be obtained with alhyl halides of low molecular weight, while alkyl halides of higher molecular weight (for ex? ole he..;.. give 3 phine of the highest molecular weight in herto prepared by this method, is. the octyl-phosphine C H PH is only obtained in a yield of a few percent. When hydrogen phosphide is reacted with oletins in the presence of acid catalysts under pressure lGO atmospheres gauge) a mixture of all possible phosphines is formed in a yield of about 67%. Said reaction mixture only contains small amounts or" primary phosphines.

Thus it was hitherto not possible to obtain good yields of pure primary organic phosphines by one of the known methods.

it has now been found that primary organic phosphines can he produced in a high purity and-if the allay! group contains more than 4 carbon atoms-also in a very good yield, when known complex compounds formed under suitable conditions from a Lewis acid, preferably aluminum chloride, and hydrogen phosphide, are reacted in an exo hermal reaction a monoor dihalogenated ocarbons in which the halogen atom is bound to an aliphatic carbon atom and from the reaction products thus obtained the primary organic phosphines are isolated from the organic phase after hydrolytic decomposition. Secondary phosphines are formed only in an inferior amount as "byproducts.

The process of the invention is carried out in a manner such that a melt of a complex compound produced at a temperature in the range from about 20 C. to about 150 C. in known manner from a Lewis acid, preferably anhydrous aluminum c loride, and hydrogen phosphide in a molar ratio of irl is a mitted in an inert gas 2 .osphere, such as nitrogen, carbon dioxide or noble gases, with a mono or dihalogenated hydrocarbon in which the halogen atom is bound to an aliphatic carbon atom, at a rate such that by the evolved reaction heat a reaction temperature is maintained at which the reaction mixture is present in the liquid phase.

In the reaction of the A1C1 .Pl-I complex compound the reaction temperature suitably ranges between the meltiug point of the complex compound of 80 C. and 133 C. Substantial differences in the yield have not been ob served in said temperature range. When the reaction has started the melting point of the complex compound is reduced and the further reaction can then be carried out also at -60" C. Inert solvents may concomitantly be used without special advantages being obtained since the complex compounds are in most o sparingly soluble in organic solvents. The application of superatmospheric pressure may be of advantage, above all when the organic halide is gaseous at the melting temperature of the complex compound, even if the splitting off of gaseous hydrogen chloride is hindered by superatrnospheric pressure.

As Lewis acids there are mentioned, in addition to aluminum chloride, other aluminum halides such as aluminum bromide, and furthermore zinc chloride, iron trichloride and boron-trifluoride.

Suitable monohalogenated hydrocarbons are alkyl halides, for example methyl, ethyl, propyl, isopropyl, primary, secondary tertiary butyl, primary isobutyl, arnyl, hexyl, octyl, nonyl, decyl, dodecyl, tetradecyl, hexadecyl, and octadecyl chlorides; cycloalkyl halides, for example, cyclopentyl chloride and cyclohexyl chloride; arallcyl halides, for example benzyl chloride, and the corresponding b Acr the addition of 1 es and iodides. about -80% of the stoicbioznetric amount of organic halide required for the formation of the primary organic phosphine; the light yellow reaction mixture becomes dark brown while foaming and the temperature decreases indicating the end of the reaction. The reaction miX- ture formed which is liquid at room temperature is decomposed in an inert gas atmosphere with ice Water and hydrochloric acid, the organic phase is separated and the formed primary phosph. e is pus d by lation.

As monohulogenated hydrocarbons are suitable halides in which the organic component represents a straight chain or branched aliphatic hydrocarbon radical and the hal gen atom is bound to a primary, secondary or tertiary carbon atom, or an alicyclic or aralkyl radical, Chlorides and bromides are preferred since iodides give small yields of primary phosphines on account of secondary re actions.

Alternatively, alkylene dihalides, for example, 1,1 0 dccamethylene dibromide, and analogous products can be used, in this case bifunctional primary phosphines being obtained.

The following examples serve to illustrate the invention but they are not intended to limit it thereto.

Example 1 A suitable reaction vessel was charged with 3 mols (325 grams) of pulverized, anhydrous aluminum chloride and, after having carefully scavenged with nitrogen which is free from oxygen, hydrogen phosphide was introduced at 75-80 C. while stirring and at a rate of about 18 liters per hour. 'It has proved advantageous to heat the reaction mixture near the end of the reaction to 82 C. and repeatedly to cool by several degrees for a short time in order to enable the formed complex compound to crystallize out from the melt. Thus the absorption of hydrogen phosphide was increased. As soon as the reaction mixture has melted at 82 C. and crystallization set in to a considerable extent at 80 C. the absorption of hydrogen phosphide was terminated. The hydrogen phosphide was preferably produced from aluminum phosphide by decomposition with dilute acid.

l-chlorobutane was dropped, while vigorously stirring at 75-80 0, into 3 mols of the aluminum chloride/hydrogen phosphide complex compound thus obtained. The l-chlorobutane was added at a rate such that the temperature was maintained by the evolved reaction heat. Within 2 /2 hours 2.4 mols (80% of the theoretic amount required for the monosubstitution) were added. The light yellow reaction mixture now turned dark brown with the formation of foam and simultaneously no more heat was evolved on dropping in the alkyl halide, so that the addition was interrupted. The reaction mixture was then slowly decomposed, while stirring Well in a flask filled with nitrogen, with l-1 /2 kilograms of ice and about 50-80 cc. of concentrated hydrochloric acid. A water-insoluble upper layer separated which, after having been separated, dried and distilled, yielded 89 grams (37% of the theory, calculated on the alkyl halide used) of n-butyl-phosphine having a boiling point of 75.5 C. under a pressure of 732 mm. of mercury; n =1.4372.

As by-product 24 grams of di-n-butyh hosphine (16% of the theory) were obtained having a boiling point of 167 C. under a pressure of 732 mm. of mercury.

Example 2 1.81 mols (72.5%) of n-decyl bromide were introduced as described in Example 1 within 1 /2 hours into 2 /2 mols of the aluminum chloride/hydrogen phosphide complex compound prepared in known manner. After having worked up the reaction mixture, 215 grams of pure ndecyl-phosphine (68.5 of the theory) were obtained hav ing a boiling point of 65-67 C. under a pressure of 3 mm. of mercury; n =I.4S91.

Example 3 1.67 mols of n-hexadecyl chloride (83.5%) were added as described in Example 1 within 2 hours to 2 mols of the aluminum chloride/hydrogen phosphide complex compound and the reaction mixture was worked up in known manner. 353 grams of n-hexadecyl-phosphine were obtained (82% of the theory) having a boiling point of 169 C. under a pressure of 7 mm. of mercury; n =1.4635.

Example 4 3 mols of the aluminum chloride/hydrogen phosphide complex compound were reacted as described in Example 1 within 2 hours with 2.1 mols (70%) of tertiary butyl chloride. The yield of tertiary butyl-phosphine amounted to 1.05 mols (50% of the theory). The product had a boiling point of 60-62 C.; iZ :l.4-23l.

Example 2.5 mols of the aluminum chloride/ hydrogen phosphide complex compound were reacted as described in Example 1 within 2 hours with 1.54 mols (61%) of cycle nexyt chloride. 50 grams (0.425 mol=27.6% of the theory) of cyclohexyl-phosphine were obtained having a boiling point of 5457 C. under a pressure of 50 of mercury; =l.4862.

Example 6 Example 7 The AlCi3'PH3 complex compound was reacted as described in the preceding examples with 0.67 mol of lbutyl iodide. Monobutyl-phosphine having a boiling point of 76 C. and a refractive index 72 of 1.4372 was obtained in a yield of 37% of the theory.

Example 8 5 mols of the llCl .PH complex compound were reacted at 80-100 C. with 2.5 mols of 1,10-decane dibromide which was diluted with 1 liter of petroleum ether. The dilution with a hydrocarbon mixture served to better stir the reaction mixture which would otherwise have a high viscosity. The reaction being complete the reaction mixture was mixed with 1 liter of dilute hydrochloric acid in order to dissolve the aluminum chloride. Two layers were formed. The upper layer consisting of petroleum ether and the reaction product was dried over anhydrous sodium sulfate, the petroleum ether was distilled oil and the reaction product was distilled under reduced pressure. The pure 1,10-decamethylene-diphosphine having a boiling point of 75 C. under a pressure of 0.5 mm. of mercury was obtained in a yield of 20%.

Example 9 1 mol of the AlBr .l l-l complex compound which had been prepared in the same manner as the complex com pound of the aluminum chloride was reacted with 0.86

mol of l-hexyl bromide at 105-110" C, the melting range Examples 10-17 A complex compound having an average content of sublirnable portions of at least 90% by weight was prepared as described in Example 1 from aluminum chloride and hydrogen phosphide. Commercial aluminum chloride absorbed on the average 85-90% of the equivalent weight of hydrogen phosphide. The complex compound formed was then immediately reacted at C. with a number of organic halides. At the beginning the reaction was distinctly exothermal. In spite of this fact no additional cooling was required, it was suificient to regulate the rate of addition of the alkyl halide. The initially light yellow almost transparent addition compound became milky in the course of the reaction and distinctly turned brown while foaming after the addition of the total amount of the organic halide, whereupon the temperature decreased rapidly, even with a further addition of organic halide. The reaction was, therefore, interrupted and the reaction mixture was cautiously decomposed under a protective gas with ice and hydrochloric acid, the organic phase was separated and processed by distillation.

The results are contained in the following table: 4. A process as defined in claim 1 wherein the com- Yield of pure Molecular weight phosphine in and elementary Molar ratio percent of the analysis Refractive Boiling point] EX. Organic halide uesd AlCls-PHs theory, caleu- Density, index an mm. Hg

complexzRX lated on RX d Found Calculated n-Amyl-l-chloride 3 2. 48 MW. 105 104.1 0. 7796 1. 4131 102/760 57. 3 57. 7 12.5 12. 6 11 n-HeXy1 1-Chl0rid8 1 3:1 $199 158. 2 0. 7909 1. 4482 128/760 6. 2 60. 6 61.0 12.9 12. 8 12 n-octyl-l-olilorlde 2. 5:1. 9 62 148 146. 2 0.8082 1.4548 169/760 n-Octyl-l-bromide 2:1. 45 76 20. 5 21. 2 65.1 65. 7 13. 3 13. 1 13 l1-N0nyl-1chloride 3 2. 15 1% 1 0. 8122 1. 4571 187/760 68. 9 67. 5 14. 1 13. 2 14 n-Dodecyl-1-chl0rido 2. 5:1. 7 2(1); 6 0.8227 1. 4622 176/100 5. 72. 2 71. 2 13. 2 13. 4 15 n'CnHmd-ehloride 2. 5:1. 8 74 233 230. 4 0. 8263 1. 4638 /199 13. 4 13. 4 72. 2 73. 0 14. 0 l3. 6 16 n-cisH -l-chlorlde 2. 15:1. 5 83 285 286. 5 0. 8289 l. 4651 204/20 10. 6 10. 8 75. 6 7 5. 5 13. 5 13. 7 17 Cyclopentyl bromide 15:1. 27 15 1% 4 0. 8818 1.4899 121/760 We claim: plex compound is AlCl .PH

1. A process for the manufacture of primary organic phosphines of the group consisting of alkyl phosphines, aralkyl phosphines, alkylene diphosphines and cycloalkyl phosphines which comprises reacting a melt of a complex compound of the formula AIX .PH in which X stands for halogen, with a halogenated hydrocarbon of the group consisting of alkyl halides, aralkyl halides, alkylene dihalides and cycloalkyl halides.

2. A process as defined in claim 1 wherein the halogenated hydrocarbon is added to the melt at a rate sufficient to maintain the reaction mixture in a liquid phase.

3. A process as defined in claim 1 wherein the reaction is carried out at a temperature in the range from 50 to C.

5. A process as defined in claim 1 wherein the complex compound is AlBr .PH

6. A process as defined in claim 1 wherein the halogenated hydrocarbon is an alkyl halide containing 1 to 18 carbon atoms.

7. A process as defined in claim 1 wherein the halogenated hydrocarbon is cyclopentyl chloride.

8. A process as defined in claim 1 wherein the halogenated hydrocarbon is cyclohexyl chloride.

9. A process as defined in claim 1 wherein the halogenated hydrocarbon is alkylene dihalide.

No references cited. 

1. A PROCESS FOR THE MANUFACTURE OF PRIMARY ORGANIC PHOSPHINES OF THE GROUP CONSISTING OF ALKYL PHOSPHINES, ARALKYL PHOSPHINES, ALKYLENE DIPHOSPHINES AND CYCLOALKYL PHOSPHINES WHICH COMPRISES REACTING A MELT OF A COMPLEX COMPOUND OF THE FORMULA AIX3PH3, IN WHICH X STANDS FOR HALOGEN, WITH A HALOGENATED HYDROCARBON OF THE GROUP CONSISTING OF ALKYL HALIDES, ARALKYL HALIDES, ALKYLENE DIHALIDES AND CYCLOALKYL HALIDES. 